1. Field of the Invention
This invention relates to a method and an apparatus for conducting operations such as cutting an existing pipe for boring, removal of substance deposited on the inner surface of the pipe or protrusions extending into the pipe, and disposition of a plug of cutoff in a pipe opening of a branch pipe and, more particularly, to a method and an apparatus for conducting operations in a pipe suitable for fitting a plug of cutoff in a branch pipe communicating to a main pipe comprising the existing pipe and a newly installed pipe to thereby close an opening of the branch pipe on the main pipe side, cutting away protrusions of the branch pipe such as to remove the protrusions thereof extending into the main pipe and cutting away a portion of the newly installed pipe so as to bore a hole in the newly installed pipe from the interior thereof to thereby afford communication between the main pipe and the branch pipe.
2. Description of the Prior Art
Various methods for disposing new pipes in existing pipes, and for applying coating or lining to the inner surface of an existing pipe have been proposed and executed in order to reproduce, i.e., renew the existing pipes such as sewer pipes, water-supply pipes, gas pipes, pipes for power lines and pipes for telephone lines. According to these renewing methods, newly installed pipes are positioned in the interior of the existing pipe so as to be substantially integral therewith.
When the existing pipe being renewed in accordance with the above methods has protrusions therein as in the case of a sewer pipe having a portion of a mounting pipe, i.e., a branch pipe protruding into a main pipe the existing pipe requires removing the protrusions therein before pipes to be newly installed are disposed in the existing pipe. However, since the inner surface of the existing pipe is usually circular in shape, it is difficult to correctly cut away the protrusions.
Also, since a pipe opening of the branch pipe is closed by the newly installed pipe when the pipe is renewed according to the above renewing method, it is necessary to bore a hole in the newly installed pipe to thereby open the pipe opening of the branch pipe into the newly installed pipe. In this case, if the axis of the branch pipe is not orthogonal to the axis of the newly installed pipe, the hole corresponding to the pipe opening of the branch pipe cannot be accurately bored only by rotating a cutter around the axis extending in the radial direction of the newly installed pipe.